A memory system including a non-volatile semiconductor memory such as flash memory, or the like, called a solid state drive (hereinafter, referred to as an SSD) has been developed. In the SSD, components made of integrated circuits (ICs) such as a flash memory, a controller, a power supply circuit, a temperature sensor, and the like, are provided on a substrate. A temperature of the flash memory may become high during an operation of the flash memory. A temperature sensor detecting the temperature of the flash memory is provided. The temperature sensor periodically transmits the measured temperature to the controller. The temperature sensor and the power supply circuit are connected to the controller by an interface of the same serial communication standard, and are respectively controlled by the controller. For this reason, wiring patterns independently connected from the controller to each of the temperature sensor and the power supply circuit need to be formed on the substrate.